The present invention relates to the real-time full scope simulation of the dynamic operation of a nuclear powered electrical generating plant for training plant operators.
The increasing demand for well-trained power plant operators together with the complexity of modern day power plants, has led to the realization that the simulator is the most effective tool for such training.
Also, with advancements in nuclear power plant technology, experienced operators from time-to-time need retraining in order to be competent. An actual nuclear plant cannot provide the operator with the required experience, such as starting up, changing load, and shutting down, for example, except after years of experience; and even then, it is unlikely that he would observe the effect of important malfunctions and be able to take the best corrective procedures.
Although simulators have been used for many years, in power plant design, it is only recently that they have been used for power plant operator training. An article in the July 22, 1968 issue of "Electrical World," entitled "Nuclear Training Center Using Digital Simulation" briefly describes the installation of a boiling water reactor plant simulator. An article in the same publication in the Oct. 6, 1969 issue entitled "Huge Simulator to Ready More Reactor Operators" discusses the proposed installation of a pressurized water reactor simulator. In Volume 10, No. 5 of the publication "Nuclear Safety" published during September and October, 1969 is an article entitled "Training Nuclear Power Plant Operators With Computerized simulators;" and in the June, 1972 issue of the publication "Power Engineering" there is an article entitled "Simulators" which describes a number of power plant operator training simulators presently in use or proposed.
Design simulators usually cover only a small part of the process, and may run slower or faster than real-time; while training simulators must operate and respond in a manner identical to the actual plant. A design simulator may involve only a narrow range of conditions, while a training simulator must simulate from "cold" shutdown to well beyond normal operating conditions. A design simulator usually involves only the major process, while a training simulator should cover every auxiliary system with which the plant is concerned.
Training simulators presently in use for operator training, which are more or less complete in their simulation utilize a digital computer that is connected to control consoles that are identical in operation and appearance to the plant being simulated. Also, an instructor's console is connected to control the simulator, introduce malfunctions, initialize the simulated plant at selected states of operation, and perform other functions useful for training purposes and control of the simulator.
In order to be complete, the simulation of the reactor should include xenon calculations and their effect on reactor power at any point in time of operation. Also, in many instances, an instructor may wish to simulate the real-time operation of the plant after a time span in hours or days is supposed to have elapsed, and it is desired that the plant be in an exact condition of operation at the end of the elapsed time. Depending on the power level or condition at which it is to operate after this elapsed time, the various controls are adjusted accordingly.
However, with respect to xenon, the amount builds up slowly in the reactor; that is, it lags behind the power by about eight hours. As the xenon builds up to equilibrium, the reactor power decreases. With decreased power, the amount of xenon decreases, which permits the power to increase. This in turn increases the production of xenon, which create oscillations of xenon that lag behind reactor power in the neighborhood of the 8 hour period. Thus, in order to have an accurate simulation of the effect of xenon at some predetermined time in the future, it is necessary to accelerate the xenon simulation. Also, inasmuch as the amount of decay heat, which depends on the reactor operating time and power output, influences the xenon build up, it is desirable that such influence be included in the xenon simulation.
During actual operation the effect of xenon on reactor power is compensated by the addition and subtraction of boron; thus, it is also desirable that the boron concentration be known at the end of the predetermined elapsed time span.
It is apparent that without the benefit of an accurate xenon acceleration simulator, an accurate simulation would require the running of the simulator for the elapsed time that the instructor desires; and an attempt to calculate for a long elapsed time would prevent accuracy and limit the flexibility of the simulator. Thus, it is desirable to utilize time steps that are small enough to be accurate in their calculations and large enough to prevent an undue delay in arriving at the proper condition of operation for all operating situations both normal and abnormal.